how to count power?

[Patryk_Rebisz]

This seemingly simple match still baffles me.
Say i have a v-mount Li-Ion battery 14.8V (90Wh, 6.2Ah) and have a monitor that consumes DC12V, 1.5A. How do i calculate how long that monitor will be on with said battery?

 

[Paul F]

Convert the monitor consumption to watts:

Watts = V x Amps = 12 x 1.5 = 18watts

Battery is 90 watt-hours, meaning it will last 1 hour at 90 watts consumption.

Divide 90 by 18 watts = 5 hours

Of course, that's if the manufacturers are truthful and it is room temperature. Things change with temperature.

 

[Patryk_Rebisz]

Thx Paul!

 

[Greg_E]

It may last a little longer than that in reality, but the above calculation gives a good real world run time for your planning and to help prolong the life of your battery. I might rate it at 4 hours to be really safe.